When two paths cross, it is important to be able to provide warnings of the approach of an object, for example, a vehicle or a person, to the area where the paths cross. This is particularly so when two vehicles or a vehicle and a person approach the same intersection of vehicle paths to give operators of the vehicles and the pedestrian ample warning about the potentially dangerous situation. Many warning devices are used to notify people of oncoming vehicles. In case of railroad crossings, car drivers and pedestrians are usually notified by visual signals, such as flashing lights or traffic signals, audio signals, crossing gates, etc. In the case of emergency vehicles approaching an intersection, the public is typically notified of their approach by colored flashing lights and/or sirens mounted on the emergency vehicle. In the case of watercraft, warnings of an approaching navigation obstacle include flashing lights and audio signals on the known obstacle, radar, etc.
These warning devices are typically either on constantly, as in the case of a buoy, or activated when the potentially dangerous situation begins to present itself such as physically, usually visually, detecting an approaching vehicle and causing the warning device to be activated. Physical detection can be adversely affected by such parameters as sensitivity to weather conditions, surrounding terrain, etc. Also, when physical detection is used, the lead time between the activation of the warning device and the time the vehicle crosses the intersection of paths, may be affected by the speed of the approaching vehicle such as in situations where there is a presence at a set distance from the vehicle path crossing. A good example is the locator devices at a railroad crossing. The train detectors are generally set a standard fixed distance from the road crossing. If the detector is 1 mile from the crossing, the advance warning when the train is going 100 miles an hour is 1/10 the time when the train is going 10 MPH. When warning signals are active all the time, such as ambulance sirens or flashing lights on a buoy, the advance warning is limited by how far the light and sound of the warning device travels and how far the pedestrians and vehicle operators can see.
Another problem with known warning systems today is that they can be very expensive to install in remote areas. While the advent of use of solar powered batteries has helped to address this, cost of the units themselves, installation, monitoring and maintenance of these systems can still be a barrier to putting warning systems everywhere that a potentially dangerous situation exists. Also, with regard to marine vehicle crossings, it is very difficult to use any other system than a constant warning device because of the difficulty and cost of placing sensors to detect the approach of a watercraft.
What is needed is a low-cost but effective and reliable system and method for among other things, warning pedestrians and vehicle operators of the approach of vehicles at vehicular path crossings.